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Primeur weekly 2018-01-29

Focus

European Commission explains why Joint Undertaking is well suited as legal instrument to help create EuroHPC ecosystem ...

Combination of top-down initiatives like EuroHPC and bottom-up science driven projects make European exascale effort healthy ...

Quantum computing

Quantum race accelerates development of silicon quantum chip ...

Quantum control: Scientists develop quantum metamaterial from complex twin qubits ...

New metal-semiconductor interface for brain-inspired computing ...

Researchers from TU Delft combine spintronics and nanophotonics in 2D material ...

Retrospective test for quantum computers can build trust ...

Particle collision in large accelerators is simulated by using a quantum computer ...

Focus on Europe

EOSC-hub to launch integrated services for the European Open Science Cloud ...

Supercomputing Frontiers Europe 2018 launches invitation to participate ...

CESNET and GÉANT deploy 300 Gbps wavelength in R&E community ...

PRACE SHAPE Programme supports two further SMEs ...

Hardware

Most powerful Dutch GPU supercomputer boosts new radio telescope ...

Asetek receives order from Fujitsu for Institute of Fluid Science at Tohoku University ...

Applications

Researchers use sound waves to advance optical communication ...

NIST's superconducting synapse may be missing piece for 'artificial brains' ...

Scientists get better numbers on what happens when electrons get wet ...

UNSW Sydney scientist Michelle Simmons is Australian of the Year ...

San Diego County invests in new UC San Diego fire detection networking ...

Solving science and engineering problems with supercomputers and AI ...

Purdue-affiliated start-up designing next-generation hardware, software to propel computer intelligence to next level ...

Scientists pioneer use of deep learning for real-time gravitational wave discovery ...

Dynaslum research team publishes in Nature Scientific Data ...

University of Texas at Arlington researchers use simulations to study brain damage from bomb blasts and materials for space shuttles ...

Ohio Supercomputer Center helping Ohio University researcher revolutionize drug discovery with RNA in the spotlight ...

Cells of three aggressive cancers annihilated by drug-like compounds that reverse chemo failure ...

Sensor the size of a nitrogen atom investigates hard drives ...

Retrospective test for quantum computers can build trust


This cartoon illustrates how a quantum computation performed over the Cloud could be verified after completion with the help of a network of quantum computers. Researchers in Singapore and Japan have published in Physical Review Letters a proposal for such a scheme. Image credit: Liu Jia & Aki Honda / CQT, NUS.
23 Jan 2018 Singapore - Tech companies are racing to make quantum computers available to customers. A new scheme from researchers in Singapore and Japan could help customers establish trust in what they get if they buy time on such machines - and protect companies from dishonest customers.

Quantum computers have the potential to solve problems that are beyond the reach of even today's biggest supercomputers, in areas such as drug modelling and optimisation.

"Our approach gives a way to generate a proof that a computation was correct, after it has been completed", explained Joseph Fitzsimons, a Principal Investigator at the Centre for Quantum Technologies at the National University of Singapore and Assistant Professor at the Singapore University of Technology and Design.

Joseph Fitzsimons carried out the work with colleague Michal Hajdusek and collaborator Tomoyuki Morimae, who is at Kyoto University in Japan. Their proposals have been published on January 22, 2018 inPhysical Review Letters.

Quantum computers today are bulky, specialised machines that require careful maintenance, meaning that people are more likely to access machines owned and operated by a third party than to have their own - like a quantum version of a Cloud service.

Customers sending off data and programmes to a quantum computer will want to check that their instructions have been carried out as they intended. This problem of verification has been tackled before, but previous solutions required the customer to interact with the quantum computer while it was running the computation.

That kind of back-and-forth communication isn't necessary in the new scheme. "If you receive a result that look fishy, you can choose to verify the result, essentially retrospectively", stated Joseph Fitzsimons. Verification guards against a quantum computer that does not perform correctly because of an accidental fault or even malicious tampering.

The improvement comes from how the calculation is checked. "The approach is completely different. We try to produce a state which can be used as a witness to the correctness of the computation. The previous approaches had some kind of trap built into the computation that gets checked as you go along", explained Joseph Fitzsimons.

The witness state registers each step of the computation. This means it must have as many bits as the computation has steps. For example, if a computation has 1000 steps, on 100 qubits, the witness would need to be 1100 qubits long.

The research team present two post-hoc verification schemes, based on different ways of testing the witness state. The first requires the customer to be able to send and measure quantum bits. In practice, this means they would need some specialized hardware and a line for sending these qubits to the owner of the quantum computer. The customer then measures the witness directly.

In the second scheme, the customer can be without any quantum tools - communication over the regular internet would do - but the quantum computer doing the calculation must be networked with five other quantum computers that help to check the witness state, playing a role as provers.

"It will be difficult to do an experiment to demonstrate post-hoc verification, but maybe not impossible", stated Joseph Fitzsimons. A challenge is the size of the quantum computers available today - the biggest are around 50 qubits. Another is that the networked setups required for the prover schemes don't exist - at least not yet.

The researchers wrap up their paper by pointing out an interesting advantage of the post-hoc verification scheme: It's not only the customer who could check that a computation was carried out correctly. The scheme allows 'public verifiability'. The witness could be checked by a trusted third party, such as a court. This could protect the company if, say, a customer claimed the computation was not done correctly to avoid paying for the service.

The paper titled " Post hoc verification of quantum computation " has been published inPhysical Review Letters120, 040501 (2018).

This paper combines results found in the following preprints: " Post hoc verification of quantum computation " by Joseph F. Fitzsimons and Michal Hajdušek and " Post hoc verification with a single prover " by Tomoyuki Morimae and Joseph F. Fitzsimons.

Source: National University of Singapore

Back to Table of contents

Primeur weekly 2018-01-29

Focus

European Commission explains why Joint Undertaking is well suited as legal instrument to help create EuroHPC ecosystem ...

Combination of top-down initiatives like EuroHPC and bottom-up science driven projects make European exascale effort healthy ...

Quantum computing

Quantum race accelerates development of silicon quantum chip ...

Quantum control: Scientists develop quantum metamaterial from complex twin qubits ...

New metal-semiconductor interface for brain-inspired computing ...

Researchers from TU Delft combine spintronics and nanophotonics in 2D material ...

Retrospective test for quantum computers can build trust ...

Particle collision in large accelerators is simulated by using a quantum computer ...

Focus on Europe

EOSC-hub to launch integrated services for the European Open Science Cloud ...

Supercomputing Frontiers Europe 2018 launches invitation to participate ...

CESNET and GÉANT deploy 300 Gbps wavelength in R&E community ...

PRACE SHAPE Programme supports two further SMEs ...

Hardware

Most powerful Dutch GPU supercomputer boosts new radio telescope ...

Asetek receives order from Fujitsu for Institute of Fluid Science at Tohoku University ...

Applications

Researchers use sound waves to advance optical communication ...

NIST's superconducting synapse may be missing piece for 'artificial brains' ...

Scientists get better numbers on what happens when electrons get wet ...

UNSW Sydney scientist Michelle Simmons is Australian of the Year ...

San Diego County invests in new UC San Diego fire detection networking ...

Solving science and engineering problems with supercomputers and AI ...

Purdue-affiliated start-up designing next-generation hardware, software to propel computer intelligence to next level ...

Scientists pioneer use of deep learning for real-time gravitational wave discovery ...

Dynaslum research team publishes in Nature Scientific Data ...

University of Texas at Arlington researchers use simulations to study brain damage from bomb blasts and materials for space shuttles ...

Ohio Supercomputer Center helping Ohio University researcher revolutionize drug discovery with RNA in the spotlight ...

Cells of three aggressive cancers annihilated by drug-like compounds that reverse chemo failure ...

Sensor the size of a nitrogen atom investigates hard drives ...